Large oriented electric fields spontaneously arise at all solid–liquid interfaces via the exchange of ions and/or electrons with the solution. Herein, we develop general methods for wirelessly monitoring and controlling spontaneous electrical polarization at conductive catalysts dispersed in liquid media. By combining electrochemical and spectroscopic measurements, we demonstrate that proton and electron transfer from solution controllably, spontaneously, and wirelessly polarize Pt surfaces during thermochemical catalysis. We employ liquid-phase olefin hydrogenation on a Pt/C catalyst as a thermochemical probe reaction, and observe that the rate of this non-polar hydrogenation reaction is significantly influenced by spontaneous electric fields generated by both interfacial proton transfer in water and interfacial electron transfer from organometallic redox buffers in a polar aprotic solvent. Across these vastly disparate reaction media, we observe quantitatively similar scaling of hydrogenation rates with the Pt open-circuit electrochemical potential (<i>E<sub>OCP</sub></i>). We combine mechanistic experiments with transition state theory to elucidate the rigorous thermodynamic and molecular origin of this electrostatic phenomenology, and conclude that spontaneous polarization plays an essential role in non-faradaic reactivity at solid–liquid interfaces.

Spontaneous charge transfer reactions govern the electric field dependence of thermochemical catalysis

ACS Spring 2022

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